Interview has 3 stages: online problem solving, home task and work with them for a whole day. You can move as fast as you can on that process. On fist stage you need to solve algorithmic task in realtime and respond on questions about "how to build system to solve that task". You're not required to write whole code alone, you have some support and hints, so you should listen carefully and explain what you want to do. Second stage is home task. You have 2-3 hours to solve it. You can't prepare to it, because there is no information about what kind of task it could be. I thought it'd be task for testing my coding skills, but it was 90% algorithmic. It's impossible to solve it without specific algorithm. If you have used that algorithm before or remember it from University - it'd be easy for you. Otherwise you should find that algorithm by yourself, understand and modify it to specific requirements, which is really hard to do in that time limits. Totally I spend 5 hours to make working solution, which was not best in terms of code quality, because I failed time limits. It was unaccepted and interview process finished. My advice is to not spend any time for naive approach, just start searching of algorithm immediately and make sure you understand it. After that start writing clean code with comments and OOP. Overall, interview was very well organized and good, with a lot of support and help.